High‐Temperature Energy Relations in Borates: Alkaline‐Earth and Lead Borate Compounds and Their Glasses

The high‐temperature energy relations in some alkaline‐earth and lead borate glasses and compounds of the same compositions are reported. The data obtained with a continuous high‐temperature calorimeter and by solution calorimetry in 2 N nitric acid were combined to give heat content versus temperature curves from 25° to 1100°C. The heats of fusion, entropies of fusion, entropy changes vs. temperature, and the free‐energy changes from crystal to glass at 25°C are given. Previously unavailable X‐ray diffraction data for strontium diborate and calcium diborate are reported.